acinclude/ax_gcc_x86_cpuid.m4.htm
author Sam Lantinga
Tue, 10 Jan 2017 08:54:33 -0800
changeset 10806 36f40b8cc979
parent 5029 5d7d48157be7
permissions -rw-r--r--
Fixed bugs 2570, 3145, improved OpenGL ES context support on Windows and X11

Mark Callow

The attached patch does the following for the X11 and Windows platforms, the only ones where SDL attempts to use context_create_es_profile:

- Adds SDL_HINT_OPENGL_ES_DRIVER by which the application can
say to use the OpenGL ES driver & EGL rather than the Open GL
driver. (For bug #2570)
- Adds code to {WIN,X11}_GL_InitExtensions to determine the maximum
OpenGL ES version supported by the OpenGL driver (for bug #3145)
- Modifies the test that determines whether to use the OpenGL
driver or the real OpenGL ES driver to take into account the
hint, the requested and supported ES version and whether ES 1.X
is being requested. (For bug #2570 & bug #3145)
- Enables the testgles2 test for __WINDOWS__ and __LINUX__ and adds
the test to the VisualC projects.

With the fix in place I have run testdraw2, testgl and testgles2 without any issues and have run my own apps that use OpenGL, OpenGL ES 3 and OpenGL ES 1.1.
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# ===========================================================================
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#     http://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html
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# ===========================================================================
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#
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# SYNOPSIS
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#
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#   AX_GCC_X86_CPUID(OP)
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#
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# DESCRIPTION
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#
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#   On Pentium and later x86 processors, with gcc or a compiler that has a
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#   compatible syntax for inline assembly instructions, run a small program
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#   that executes the cpuid instruction with input OP. This can be used to
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#   detect the CPU type.
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#
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#   On output, the values of the eax, ebx, ecx, and edx registers are stored
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#   as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
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#   ax_cv_gcc_x86_cpuid_OP.
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#
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#   If the cpuid instruction fails (because you are running a
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#   cross-compiler, or because you are not using gcc, or because you are on
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#   a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
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#   is set to the string "unknown".
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#
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#   This macro mainly exists to be used in AX_GCC_ARCHFLAG.
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#
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# LICENSE
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#
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#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
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#   Copyright (c) 2008 Matteo Frigo
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#
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#   This program is free software: you can redistribute it and/or modify it
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#   under the terms of the GNU General Public License as published by the
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#   Free Software Foundation, either version 3 of the License, or (at your
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#   option) any later version.
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#
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#   This program is distributed in the hope that it will be useful, but
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#   WITHOUT ANY WARRANTY; without even the implied warranty of
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#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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#   Public License for more details.
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#
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#   You should have received a copy of the GNU General Public License along
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#   with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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#   As a special exception, the respective Autoconf Macro's copyright owner
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#   gives unlimited permission to copy, distribute and modify the configure
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#   scripts that are the output of Autoconf when processing the Macro. You
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#   need not follow the terms of the GNU General Public License when using
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#   or distributing such scripts, even though portions of the text of the
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#   Macro appear in them. The GNU General Public License (GPL) does govern
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#   all other use of the material that constitutes the Autoconf Macro.
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#
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#   This special exception to the GPL applies to versions of the Autoconf
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#   Macro released by the Autoconf Archive. When you make and distribute a
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#   modified version of the Autoconf Macro, you may extend this special
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#   exception to the GPL to apply to your modified version as well.
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#serial 7
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AC_DEFUN([AX_GCC_X86_CPUID],
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[AC_REQUIRE([AC_PROG_CC])
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AC_LANG_PUSH([C])
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AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
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 [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
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     int op = $1, eax, ebx, ecx, edx;
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     FILE *f;
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      __asm__("cpuid"
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        : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
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        : "a" (op));
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     f = fopen("conftest_cpuid", "w"); if (!f) return 1;
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     fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
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     fclose(f);
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     return 0;
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])],
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     [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
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     [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
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     [ax_cv_gcc_x86_cpuid_$1=unknown])])
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AC_LANG_POP([C])
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])